The present invention relates generally to exercise devices, and in particular to devices used for weight training and weight lifting, such as barbells and dumbbells.
Conventional dumbbells and barbells consist of a handle with a weighted head attached at or near either end. The weighted heads may be in the form of circular plates. These circular plates are typically removable so that different or additional weighted heads may be attached as desired to vary the weight of the device. The weighted heads may also be permanently attached to the handle, or may be an integral part of the handle, as is often the case for dumbbells. Removable weighted heads are commonly in the form of cast iron plates with holes in the center to receive the handle. Permanently attached weighted heads are often made of iron, and in some cases the entire handle and weighted head assembly is formed of a single piece of material. Both removable plates and permanently attached weighted heads may be coated with a resilient material, such as vinyl, urethane, or rubber, to prevent marring of floors and other surfaces. Such coatings also help alleviate the noise that otherwise would result from the banging of the weighted heads against other equipment.
One of the chief disadvantages of conventional barbells and dumbbells is the size or bulk of the weighted heads. Large weighted heads make a barbell or dumbbell more difficult to balance and control. Thus the devices become more dangerous as the amount of weight is increased, since a person can easily lose control and drop the device. Also, the difficulty of controlling such devices lessens the maximum lifting capacity for a particular user, since the user must expend more energy to maintain balance and control over the device. The difficulty inherent in balancing and controlling a device with bulky weighted heads also increases the anatomical stress in the hands and arms of the user, thus increasing the risk of injury during exercise.
Iron or steel is typically chosen as the construction material for the weighted heads of barbells and dumbbells for several reasons. First, iron and steel are strong and durable, which extends the life of the weighted heads. Dumbbells and barbells are often used in a rough manner, and are commonly dropped or banged against other equipment. Durability is thus an essential requirement for these devices, particularly for devices designed to be used in commercial gymnasiums where heavy use is expected.
Another advantage of iron and steel is that these materials have a more attractive appearance than many other metals. This is particularly true of stainless steel. The exercise equipment market is extremely competitive, and commercially successful equipment must be not only functional but aesthetically pleasing to the user. Attractive exercise equipment encourages the user to continue with an exercise regimen, which is particularly important for those users who are not otherwise accustomed to weight training and weight lifting. Gymnasium and health club owners find that the aesthetic appearance of their equipment is significant in maintaining current members and attracting new members.
Although iron and steel have numerous advantages, they have certain disadvantages as well. Because iron and steel are relatively light metals, a weighted head constructed of these materials must be relatively large and bulky to impart a desired amount of weight. Also, although stainless steel is perhaps the most attractive material used in constructing such devices, it is extremely expensive, and thus dumbbells and barbells constructed of solid stainless steel would not be affordable by most consumers.
While it would be possible to construct weighted heads of heavier metals, such as lead for example, these metals also have undesirable qualities. In the case of lead, the softness and malleability of the metal makes construction with this material impractical. A weighted head constructed of solid lead would quickly deform during use, since such devices are commonly dropped or struck against other equipment. Moreover, lead has an unattractive appearance that would make such a device commercially unfeasible. It would therefore be desirable to develop an exercise device with weighted heads having the durability and attractiveness of a lighter material, yet also having the reduced bulk of a heavier material, thereby improving safety and increasing the user's lifting capacity.
The prior art includes a number of exercise devices comprising shells that are filled with material to impart weight. U.S. Pat. No. 1,044,018 to Calvert discloses a dumbbell and barbell having spherical heads filled with shot. U.S. Pat. No. 702,356, also to Calvert, discloses a barbell with shot-filled heads having an adjustable end plate to vary the amount of weight in each head. U.S. Pat. No. 3,334,899 to Bosko et al. discloses a dumbbell with spherical heads containing fluid. U.S. Pat. No. 4,538,806 to Wilkerson discloses a dumbbell having heads composed of a resilient material and filled with small balls, shot, a liquid, or gelatin. None of these disclosures specifically teach a device having weighted heads that are durable and attractive, yet also have the reduced bulk made possible only through the use of very dense materials. Also, since each of these devices has loose or fluid weighted material inside the weighted heads, there is always the risk of leakage or spillage of those materials.
U.S. Pat. No. 5,102,124 to Diodati discloses a barbell having weighted units composed of a plastic exterior with a weight material inside, where the weight material can be sand, cement, or a metal-based material. Diodati discloses that the weight material need not have structural strength or an attractive appearance. Diodati discloses, however, that the barbell has mounting portions in which the weighted units are placed. These mounting portions significantly increase the bulk of the disclosed barbell, and thus fail to achieve the desired object of reduced bulk as discussed above.
U.S. Pat. No. 3,464,692, 3,482,834, and 3,171,652, to Ammondson, et al., James, Jr., and Newman, respectively, each disclose dumbbells or weighted heads consisting of plastic shells filled with a liquid or solidified material such as cement. Weighted heads of this type lack the aesthetically pleasing appearance of iron or steel weighted heads. Prolonged or rough use can cause the plastic shell of these weighted heads to crack, particularly in commercial gymnasium environments. Also, the disclosed devices must include a plug that seals the aperture through which the filler material is poured into the plastic shell. These plugs may extend from the plastic shell, and thus may catch on clothing or equipment thereby creating a safety hazard. The plugs themselves degrade the symmetrically pleasing appearance of the dumbbell or barbell and thereby reduce the aesthetic qualities of the device. Finally, cement within such devices tends to crack during use and rattle inside the plastic shell, causing the devices to be noisy during exercise.
In short, none of the disclosures discussed above teach a device with weighted heads having the durability and attractiveness of a lighter material with the reduced bulk of a heavier material. Each of the disclosures teaches a device that has weighted elements that may shift, break, or leak during use. Liquid- and gelatin-filled devices are prone to leaking, while devices filled with shot may spill shot through prolonged use. Shot-filled devices are noisy as the shot moves within the device. Devices filled with concrete exhibit similar problems as the concrete cracks during use.